Is California a ‘State in Denial’ concerning its Drought?
Following the first year of near average rainfall compared to the past four years of extreme drought conditions, California has decided to retract all urban water conservation efforts for the foreseeable future. The state’s reservoirs are full and various urban water municipalities have been losing money as a result of the water conservation efforts enforced last year. This effort succeeded beyond what was projected. Now all restrictions have been dropped for, at least, urban consumers. Is this a wise decision?
The California precipitation season of July 1, 2015-June 30, 2016 has come to its conclusion and overall produced normal rainfall, the first such since the season of 2011-2012. The northern portion of the state was a bit wetter than average while the southern section was drier.
Precipitation for selected sites in California during the year of July 1, 2015-June 30, 2016 (the state’s traditional water year). In parentheses are the percentages of normal for the previous water season of 2014-2015. As one can see all sites (except for the desert town of Blythe) fared better this past year compared to the previous season of 2014-2015. The sites are organized geographically from north to south.
The improvement in the drought situation compared to last year at this time can also be seen in the latest drought monitor report.
Although the entire state remains abnormally dry at this time (top map) the areal coverage of ‘extreme’ and ‘exceptional’ drought conditions has shrunk considerably compared to a year ago (bottom map): from 47% under ‘exceptional drought’ conditions in June 2015 to 21% this June and from 71% under ‘extreme drought’ in 2015 to 43% currently. Drought Monitor maps produced by The National Drought Mitigation Center.
Most importantly (from the perspective of the state water utilities and agencies) is the current reservoir situation.
State reservoir capacities and current levels (as of June 29th). The two largest and most important reservoirs in California are Lake Shasta and Lake Oroville in far northern California where seasonal precipitation averaged about 115-120% of normal this past year and has thus filled the reservoirs to slightly above average capacity for this date (107% of average capacity for Lake Shasta and 103% of average capacity for Lake Oroville). Map from the California Department of Water Resources.
All of the above statistics help explain why all but one of the 10 state’s major urban water utilities have decided to remove all water restrictions for their customers. This is a dramatic reversal from a year ago when mandatory cuts, averaging 25% statewide, were in force. The public responded and, in many, cases exceeded the mandated cuts. See graphic below:
Actual water savings (dark blue bar), mandated water cuts (light blue bar) and current proposed cuts for this year (no bar) for the 10 largest urban water utilities in California. The base year used is 2013 when the drought became a serious issue. These 10 agencies supply water to more than 25% of California’s population. Data from the State Water Resources Control Board, graphic courtesy of the San Francisco Chronicle.
The new policy is the result of not only an improvement overall in the drought situation but a new strategy being employed by the State Water Resources Board in response to falling revenues at the various water utility agencies (the result of the successful conservation efforts by the public). The state water authorities have decided to devolve the decision for water conservation goals to each individual agency in lieu of mandatory caps set by the state. As the San Francisco Chronicle described it, “The new policy directs the water agencies to cut what’s necessary in order to maintain enough water to supply consumers in the event of three dry years. If an agency projects a 10% shortfall, for example, it needs to cut back 10%.”
The rosy picture, however, is offset by the fact that the drought situation is actually worse than the figures suggest. This winter’s Sierra snowpack (the melt of which provides a third of California’s water) peaked at 90% of normal on April 1st but has melted and runoff much faster then expected (or is normal) over the past three months, thanks to a very warm and dry spring. So despite a 90% of normal peak snowpack the actual runoff has been just 71% of normal for the northern Sierra, 77% of normal for the central Sierra, and 63% of normal for the southern Sierra. This means that the reservoir levels are likely to fall much faster than usual over the course of the summer, especially if most water conservation efforts are abandoned. What is still a big question mark, however, is how generous water distribution will be for the agricultural industry, which, of course, is by far the greatest consumer of water resources in the state.
The reality is that the drought is far from over and its effects will be far reaching: a recent survey has found that at least 66 million trees have died in the Sierra Nevada alone as a result of the now five year-long drought, portending a potentially catastrophic fire season ahead. The El Nino of this past year (which only brought a normal season of rain and snowfall) has transitioned to a La Nina pattern which may portend a drier than average winter this year and next (although not necessarily, see Jan Null’s excellent analysis of the affect La Nina has on U.S. precipitation anomalies here. Even if the coming winters bring normal precipitation to California, water conservation will remain necessary for the foreseeable future as the state’s population continues to grow and the aquifers in the Central Valley continue to drop. Furthermore, as this Stanford University report published last year points out, warming temperatures as a result of AGW are likely to increase the frequency and intensity of drought impacts in California going into the future. Even if precipitation is normal the warming temperatures are likely to result in diminished snow accumulations in the Sierra Nevada with earlier spring melts thus also diminishing the state’s so-called ‘water bank’.
The above graphic of the PMDI (Palmer Drought Index) illustrates just how prolonged the drought in California has been and how far it still has to go before the drought can be said over. Source: NWS Climate Prediction Center.
Record June Monthly Heat Records set at Phoenix (actually tied), Las Vegas, Death Valley and other Sites in the Southwest
On a side note, this June has been the warmest such on record for both Las Vegas and Phoenix (a tie in the Phoenix case). The June average monthly temperature in Las Vegas appears to be 93.0° which surpasses the previous record for the month set just last year (91.9° in June 2015). Phoenix averaged 94.8° which has tied its previous warmest June on record of 94.8° set in 2013. The POR for Las Vegas is since 1937 and for Phoenix since 1895. Of course, both these sites have seen explosive population growth and urban development over the past decades and this has certainly contributed to their ever-increasing summer warmth. However, smaller cities in the Southwest have also seen their record June average monthly temperatures exceeded this June so the ‘urban heat effect’ cannot be entirely attributed to the month’s record warmth (these are preliminary figures as of June 29th):
Death Valley, CA: 101.9° (old record 101.0° set in 2013) POR 1911-
Needles, CA: 97.7° (old record 96.8° set in 2006) POR 1941-
Winslow, AZ: 77.6° (old record 77.1° set in 2013) POR 1915-
Bishop, CA: 76.5° (old record 75.9° set in 2015) POR 1943-
UPDATE: June 30th has seen a powerful influx of monsoon moisture and most of the above records I listed are now in doubt! I will update the above figures once the final temperature reports for June 30th come in after midnight July 1st.
Christopher C. Burt
Weather Historian
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